Figure 3.
Expanded NOESY (300-ms mixing time) contour plot of the [PhIP]dG⋅dC 11-mer adduct duplex in D2O buffer at 25°C showing the NOE connectivities between the base protons and their own, and 5′-flanking sugar H1′ protons for dA3 to dA9 (solid lines) and dT14 to dT20 (dashed lines). The connectivity is disrupted in the modified strand at the dC5-[PhIP]dG6 step. The dC7(H6)-[PhIP]dG6(H1′) cross peak is boxed. The connectivity is very weak at the dG16-dC17 step (boxed). dC5*, dC7*, and dC17* designate the H6 to H5 cross peaks. PhIP-DNA cross peaks are 1, PhIP(H3′, H5′)-dG16(H1′); 2, PhIP(H2′, H6′)-dG16(H1′); 3, PhIP(H5)-dG16(H1′); 4, PhIP(H7)- dG18(H1′); and 5, PhIP(H2′, H6′)-dG18(H1′). The dC17 exchange cross peaks and minor conformer cross peaks are a, C17(H6) major to C17(H5) minor; b, C17(H6)-C17(H5) minor; c, C17(H6)-C17(H1′) minor; and d, C17(H6) minor to C17(H5) major.